Intercommunicating trunking system.



L'. R. coRwIN'. GOMMUNIGATING TRUNKING SYSTEM. l APPLICATION HL2 Mu 9.190s.

INTER Patented Apr wrmsssss:

` INVFNTOR:

1HE-Mamas PEIRRS co., wAsHlNaraN. n, c.

Y drawing, illustrating same.

dy Invention relates to Intercornmunicat- Unir srA"r Rs ATRNT ormoni.

RLMER R. CORWIN, ORCIIICAGQILLINOIS," AssIeNoR To CORwIN TELEPHONEMANUFAC- rIIRINe COMPANY, or CHICAGO, ILLINOIS, A CORPORATION OFILLINOIS.

IN'rnRcoIi/IMUNICATING TRUNK'INCT SYSTEM.

Specification of Letters Patent.

Patented April ao, 1909.

Application filed May 9, 1908.l Serial No. 431,948.

To all whom 'it may concern; l

Be it known that I, ELMRR R.. CoRwIN, a citizen ofthe United States ofAmerica, residing at Chicago, in the county of Cook-and State ofillinois, have invented a new and useful lntercommunicatingTrunkingSystem, of which the following is a specii'ication, reference being hadVto the ,accompanying ing telephone systems and deals in particularwithtrunking arrangements or such systems adapted to trunk with magnetoexchanges.

rlhs principal Objects of my ,inventionare' to provide'improved trunkingarrangements telephone systems and magneto exchanges; to provideimproved means `for signaling the magneto exchange from thevarionsfstations oi the iiitercommunicating telephone system,

to provide improved talking circuits between common batteryintercommunicating telephone systems and magneto telephone systems; toprovide improvedmeans for receiving and handling incoming trunk callsfrom a magneto exchange, in such an intercommunicating telephone systemand to rovide other improvements in' a full-metallic common-batteryintercommunicating telephone system having indicating ringing and,

be connected with any of the other stations on the system as desired,for conversation between any two parties on the system, without theintervention of the ordinary telephone central switchboard,such'connection also. permitting any of the other parties on the systemto simultaneously converse with each other. At each station on thesystem is also provided switching mechanism associated withia centralsource of ringing current, whereby each of the parties on the system mayring any ofthe other stations as desired. to signal same forconversation. In addition to the above the system also providesswitching mechanism and `suitable apparatus whereby any of the partieson the system ymay ca lly out to magneto centra-l exchange over'suitabletrunklines, one ofthe stations on the system (called the attendantsstation) being provided with a signaling device on each` oi the trunklines for receiving incoming trunk callsfrom the magneto centralexchange7 and means whereby any oi' tho other stations of the system maybe called to 1 respond to the incoming trunk calls. The accompanyingdrawing illustratesdiagrammatically a 'number of stations and trunklines onV the system of my present in'- vention, in connection withsuitable mechamsm and connections for operating and K Autilizingthesystem. for trunking between intercommunieating'i Theapparatus atthevarious stations v 1, 2,

3, etc. iis included betweenlines f g, gi, i 7c,

etc. respectively. y Y,

Each of the stations on the system is provided With a plurality oi'push-button keys such as keys T, T2, H, l, 2, 3, etc., each` key beingprovided with a pair of spring contact' members 4 adaptedA to engage apair of contact members 6 7, respectively, when the push-button 8 isdepressed, and adapted to lock in this depressed osition so as to keepAthe saidcontacts closed):l Each push-button switch or key, except thehome keys H H, is

alsoprovided with a 'contact member'lO,z

adapted to engage contact member 7 when the push-button 8 is depressedpast the locking position. All ofthe keys at any one station on thesystem are connected with a common locking mechanism whereby thedepressions of any one oi the push-buttons 8 releases anyoi the otherkeys at this station which may be in locking osition, and allows same,to return' to norma position, each key being so constructed that it willreturn to its normal osition when the locking mechanism `is re eased. Asthere are known in the art several diiierent locking keys and banksofkeys'v which` could be readily adapted for use in connection with thisinvention, it is not thought to' vbe necessary to herein describe, indetail, any articular locking lierein shown. In this connection it isbelieved to be suilicient to merely state that each oi' the keys shown nin the drawing locks ina position in which spring members 4 and 5engagecontacts 6 and 7, respectively, 'and that eachkey, `eX- cept thehome keys H H, is capable of, being Jfurther f depressed until contact 7"engages oontact'lO, notv locking in this latter position lio butreturning to the aforesald locking position when the pressure is removedfrom the button S.

The local lines of the intercommunicating telephone system aredesignated on the drawing by c, d and e, respectively, the trunk linesbeing designated by a and l), respectively. Each or' the keys at astation is adapted to connect the transmitter 19 and receiver 2O ot thatstation across the corresponding local lines of the system, or acrossthe corresponding trunk lines of the system, each home key H beingadapted to connect the home transmitter 19 and receiver 20 across thehome line.

Each of the telephones on the system is provided with a ringer 11 whichis normally connected to one limb of its home line through'suitableswitch-hook contacts. The ringers 11 11 are all connected to one pole orthe ringing battery 12 while the ringing contacts 10 10 of the variouskeys are all connected to the opposite pole of the rin-ging battery 12.When any one of the keys or a certain line is depressed to ringingposition, itv closes the circuit of ringing battery 12 through theringer 11 of the said line, as will be hereinafter traced, and therebyrings the ringer to signal the party at that station to the telephone.

Each of the trunk lines of the system is divided into two parts, a parta (or b) common to all of the local stations of the intercommunicatingsystem, and a part A (or B) eX- tending to the ma neto exchange. The twoparts of each trun line are inductively connected for talking purposesby a repeating coil 34 35 and condensers 17 and 18 connected in circuitwith the respective sides'oic the repeating coil 34 35, so as to keepthe magneto end of the trunk line separate from the common battery endof the trunk line. Each of the local lines c, d and c of the system, andeach of the local portions a and Zi of the trunk lines, are suppliedwith talking current `from talking battery 14 over a pair of impedancecoils 15 36 connected to the respective sides of each of the metalliclines. The condensers 1S 18 are for the purpose of keeping the circuitsof battery 14 normally open across the corresponding trunk lines. Thecondensers 17 17 are for the purpose of allowing conversation to becarried on through the corresponding repeating coils 34 35, 34 35, butat the same time preventing ringing current sent from the magnetoexchange, from flowing through the windings 34 34 of the correspondingrepeating coils enough to shunt the corresponding ringers 16 16 andthereby render same unresponsive to the ringing current, each condenser17 being or small capacity, preferably of one-half of a microfarad, forthe purposes stated. The condensers 17 17 and 18 18 are connected in themiddles of the corresponding windings 34 34 and 35 35, so as to properlybalance the trunk lines. The ringer-s 16 1G are bridged across thecorresponding trunk lines A and B to be rung from the magneto exchangeto signal the attendant of the intercommunicating system to answer theincoming trunk calls. Each ot the trunk lines A and B is provided with akick-coil for throwing the corresponding drop at the magneto exchange,to signal the exchange operator to answer an intercommunicating outgoingtrunk call. One winding 42 ol each of the kick-coils is bridged acrossthe corresponding trunk line A (or B), the other winding 43 ol" eachkiekcoil being connected -lrom the pole of battery 12 to which ringers11 11 are connected, to one limb of the local portion et thecorresponding trunk line (t (or b). The depression o'll any one of thekeys on a trunk line, to ringing position, closes the circuit ot battery12 through the winding 43 of the corresponding kick-coil and therebyproduces an impulse of current in the winding 43 which induces animpulse of current in the corresponding winding 42 and the magneto endot the trunk line A (or B), and thereby throws the correspondingtrunk-line drop at the magneto exchange.

To show how one party on the system calls another party on the systemand how connection is made l'or conversation between these tvo parties,l will assume that the party at station 1 calls the party at station 3,and will trace the operations and connections neeessary to enable theparty at sta.- tion 1 to converse with the party at station 3. lt willbe understood that any party on the intercommunicating system may calland converse with another party on the system, in a manner similar tothat next hereinbelow described, even ilI other stations on the systemare busy; the ringing circuits having one individual conductor, and acommon-rcturn, foreach ringer, and the talking circuits being metallicthroughout. ln calling the party at station 3, the party at stationl-.tirst dcpresses his push-button key 3 to the ringing position, thatis, until contact 7 thereof cngages contact 1.0, and thereby closes acircuit 'lrorn ringing battery 12 through conductor 21, contacts 1() 7ol key 3 at station 1,limb 2f. oi line e, contacts 41 40 at theswitch-hook of station 3, ringer 11 o'll station 3, and conductor 23back to battery 12. The current l'roni battery l2 now flowing throughthis circuit rings the ringer 11 at station 3. When the party at station1` has thus rung station 3 sutliciently he releases his key 3 whichreturns to locking position, that is, to the position in which springmembers 4 and 5 engage contacts 6 and 7, respectively, contacts 10 7being now open, and then removes his rcceiver 2() from the switch-book25 which bridges his transmitter 19 and receiver' 20, through conductors29 and 3() oi station 1,

ll tl Y and through contacts 4 6 and 5 7' of key 3 at station 1, acrossthe limbs 28 and22 of `line e.v

Conductors 29 and 3() extend to all ofthe spring members 4` and 5,respectively, o1 the several push-button keys or switches at thisstation. The party at station 3 answers his call by lifting his receiver20 from the switchhook 25 which disconnects contacts 40 and 41 andconnects contacts 26 and 27, and then depresseshis home key H' tolocking position which bridges his transmitter 19 and receiver 20across'the limbs22 and 23 o'l' his metallic line c. NovT the talkingcircuit is closed from transmitter 19 at station 1.,v

20, at station 1, back to transmitter 19 at` station 1. This talkingcircuit is fed Ywith current from talking battery 14throughimpedance'coils 15 and 36 of line e.

high impedance and of low resistance conipared with the resistance ofreceiver 20, and

is provided as a shunt around receiver 20 so as to take most oi thedirect-current supply flowing through the transmitter 19 and at thesaine time allow receiver 20 to take approximatelyall of the ,talkingcurrents 'passing through the transmitter 19. Thedirect current whichsupplies the transmitter 1.9 is thus shunted Yfrein thegreceiver 20 sothat the latter will not become demagnetized or overmagnetized thereby.When the conversation between parties 1 and 3 is ycompleted theseparties hang up their receivers on their respective switch-hooks, whichopens the circuits 'of their talking sets at the respective switch-hooksand thereby stops the ilow of current from battery 14 over theaioretraced talking circuit between stations f1- and 3. Party 1 leaveshis key 3 depressed untilhe desires to use his line again, either incommunication With station 3 or With any 4of the other stations or trunklines of the` system; The depressionl of any of the otherkeys at station1, when` it is desired to again use the talking set at station 1,releasesfthe key 3 as hereinbefore stated. Party 3 alsoleaves his homekey H depressed untilhe desires touse his talking set again,v his key Hbeing restored by the depression ofany of his other,

keys, as tion 1. Y

`1f any of the parties of the intercommunieating system desires to makean, outgoing trunk call over a trunk line, as, for example, the party atstation 2 calling out over trunk just stated in connection with stalinea'A, he first depresses his trunk key (or T2) corresponding to the trunkline, to

locking position, which closes the circuit oi' The irn` pedance coil 31at each of the stations is of ringing battery 1.2 through conductor 23,

VWinding' 43 of the kick-coil associated with Vfrom battery 12 throughthis circuit causes Winding 43 of the kick-coil toinduce an inipulse oiVcurrent in the Winding 42 oi the kickcoil, which latter impulse ol'current traverses the trunk line A leading to the magneto exchange andthrows the corresponding trunkline drop at the magneto exchange. Now thecalling party at station 2 releasesV his trunk key which returns tolocking position so that contacts 4 and 5 thereoiI engage contacts 6 and7, respectively, and then removes his telephone receiver 2() 'from theswitchhook 25 Which connects `contacts 26 and 27 and thereby bridges histransmitter 19 and receiver `2() through conductors 29 and 30 ol' hisstation, and contacts 4 6 and 5 7 oi' his depressed trunk key, acrossthe limbs 32 33 of the `trunk line a for conversation with the magnetoexchange.V The conversation may now be carried on Withv the partyconnected through the magneto exchange, over the trunk line a A, throughthe repeating coil 34 35 associated With the trunk line. The transmitter19 at station 2 is su plied With talking current from battery'14 throughimpedance coils 15 and 36 of the trunk line to Which sta tion 2 isconnected, limbs 32 and 33 oil the trunk line, contacts 6 4 and 7 5 o1'the depressed trunk key,`conductors 29 and 30,01'

station 2, and contacts 27 26 and impedance coil 31 of station 2. Whenthe conversation is completed the party at station 2 hangs up hisreceiver 20 `en the switch-hook 25 and thereby breaks the circuit ollbattery 14 through his telephone. The party at station 2 may now depressthe depressed trunk key from locking position to ringing position andthereby cause the kick-coil 42 43 to throw the disconnect 'drop at themagneto exchange, as herein-before described in connec-V tion With'theline drop at the magneto exchange. The party at station 2'leaves histrunk key `depressed until he desires to use histalkine` set a V'ain histrunk ke bein restored to normal position by the depression of any olhis other keys, as stated above iny connection. Withfstations 1 and 3.

VJhen the operator at the magneto exchange desires a connection With astation of of the contacts of the key are open.

29 and 30 of station 1 and contacts 4 6 and 5 7 of the depressed trunkkey at station 1, across the limbs 33 of the trunk line (L (er Zi). Nowthe attendant conversos With the party connected from the magnetoexchange over the trunk line and learns trom him the station of theintercommunicating system with which communication is desired. Assumingthis latter station to be station 2 oi the intercommunicating system,the attendant calls station 2 by depressing his key 2, at station 1, toringing position which signals the party at station 2 by closing thecircuit of ringing battery 12 through conductor 21, contact 10 7 or key2 at station 1, limb 22 of line d, contacts 11 10 of station 2, ringer11 orn station 2, and conductor 23 back to battery 12. Current flowingthrough this circuit rings the ringer 11 of station 2 Which signals theparty at this station. When the attendant depresses his key 2 to signalthe party at station 2 he automatically releases his depressed trunk keyT (or T2) and restores same to normal position in which position all Key2 of station 1, being now released and moving to locking position,bridges the telephone transmitter 19 and receiver 20 of station 1 acrossthe limbs 23 22 of line d, as hereinbefore described. When the party atstation 2 answers the signal oi his ringer 11, he depresses his heinekey H to locking position and removes his receiver 2O from theswitchhook 25 which bridges his transmitter 1Q and receiver 2O acrossthe limbs 28 22 of his line d, as hereinbefore described. The attendantnow converses with the party at station 2 and instructs him to makeconnection With the calling trunk line c (or t) to answer the incomingtrunk call. The transmitters 19 19 of stations 1 and 2 are now suppliedwith talking current from battery 14 through impedance coils 15 and 36of line d, in a manner similar to that hereinbefore described. 'Theattendant now hangs his receiver 2O upon the switch-hook 25 which breakshis transmitter bridge across the limbs et line d as Will be readilyunderstood. New the party at station 2 depresses his trunk key ll (orT2) corresponding' to the calling trunk line, Which releases iis homekey H and thereby bridges his transmitter 19 and receiver 20 throughconductors 29 and 30 ol station 2, and contacts e1 6 and 5 7 of thedepressed trunk key at station 2, across the limbs 32 33 oi the callingtrunk line. Non' the party at station 2 may converse With the party Whois connected through the magneto central exchange and the trunk line A a(or B b), through the medium of repeating` coil 34 35 of thecorresponding trunk line, transmitter 19 of station 2 being suppliedwith talking current from battery 14 through impedance coils 15 and 36oi the calling trunk line, as hereinbefore described, Then theconversation is completed and the party at station 2 hangs his receiver2O on the switch-hook 25 he breaks the bridge of his talking set acrossthe trunk line with which his talking set is connected, and therebystops the ilow of current from battery 14 through his transmitter 1E).The party at station 2 may give a disconnect signal to the magnetoexcl'iange by depressing his depressed trunk key to ringing positionwhich sends an impulse of current .trom battery 12 through Winding 13 olthe corresponding kick-coil, and thus induce :in impulse of currentthrough the winding 42 olI the said kick-coil which current traversesthe corresponding trunk line A (or B) and throws the disconnect drop atthe magneto exchange, hereinbe'fore described. rl`he party at station 2leaves his trunk key depressed to locking position until he desires touse his talking set again when the depression of any of the other keysat his station releases the depressed trunk key.

It will be readily seen that the ringing and talking keys of this systemare self-indicating, that is, they indicate the party with Whomconversation was last had, or, in the case of calling a party who doesnot respond, they indicate the station with which communication isdesired, so that the calling party may again readily depress the properkey to ringing position to signal the called party a second time.

l do not Wish to limit this invention to all of the particular detailsherein shown, as many modi'lications ol saine may be made Withoutdeparting from the scope of the appended claims.

Viral; l claim my invention is:

1. 11n interconn'nunicating tcleplnme system having a plurality of locallilies common to a plurality ci stations, a trunk line extend.- ing fromthe intereoinmunicating system to a magnetic exchange, a repeating coilinductiyely connecting one oi the said. local lines with the trunk linewhereby conversation may be carried on from the various said stationsover the trunk line, a kick-coil having one winding bridged across thetrunk line at the interconnnunicating sjysteni, and means at the Varioussaid stations for causing the kick-coil to throw a drop on the trunkline at the magneto exchange.

2. An intereonnnnnicat'ii1g telephone system h I ying a plurality o1alocal common-battery 1ines common to a plurality of stations, a trunklino extending lrom thc interconnnunicating system to a magnetoexchange, a repeating coil inductively connecting one ol the local lineswith the trunk line for talking purposes whereby the comn'uiii-batterylocal line is kopt separate from the magneto trunk line, a kick-coilhaving its primary winding connected. with the interconnnunicatingsystem and its secondary Winding bridged across the trunk line, andmeans for sending an iin- Al l) pulse of current through the primary ofthe kick-coil to induce an impulse of current in the secondary of thekick-coil and thetrunk line, to throw a drop connected with the trunkline at the magneto exchange.

3. An intercommunicating telephone system having a plurality of locallines common to a plurality of stations, a trunk line extending from theintercommunicating system to a magneto exchange, a repeating coilinductively connecting one of the lo'cal lines with the trunk line fortalking purposes, a kickcoil associated with the trunk line at theintercommunicating system for throwing a drop connected with the trunkline at the magneto exchange, and a condenser in series with thetrunk-line side of the repeating coil whereby any considerable portionof the impulse of current produced in the ltrunk line by the kick-coilis kept from flowing through the repeating coil.

4. An intercommunicating telephone system having a plurality of locallines common to plurality of stations, a trunk line extending to amagneto exchange, a repeating coil inductively connecting one of thelocal lines with the trunk line for talking purposes, a pair ofcondensers in series with the respective windings of the repeating coil,kick-coil at the intercommunicating system having its Vsecondary bridgedacross the trunk line, and means for causing the kickcoil to send animpulse of current over the trunk line to throw a drop at the magnetoexchange. v

5. An intercommunicating telephone system having a plurality of locallines common to a plurality of stations, a trunk line extending from theintercommunicating system to a magneto exchange, a kick-coil Vhaving itssecondary bridged across the trunk line at the intercommunicatingsystem, a suitable source of current at the intercommunicating system,and suitable ringing keys at the respective stations of theintercommunicating system whereby a party at any oi the vsaid stations my send an impulse oi current through the kick-coil to cause the lattervtoA throw a drop associated. with the trunk line at the magnetoexchange.

5. An intercommunicating telephone systeni having a plurality of locallines common to a plurality of stations, a source oic talking currentfor the local lines, impedances feeding talking current from the said.source to the various local lines, a trunk line extending from theintercommunicating system to a magneto exchange, a repeating coilinductively connecting one of the local lines with the trunk line fortalking purposes, a pair of condensers connected. in` series with therespective windings of the repeating coil, a kickcoil at theintercommunicating system having its secondary winding bridged acrossthe trunk line, ringing and talking keys at each of the stations of theintercommunicating system, a source of ringing current associated withthe intercommunicating system, and means whereby a Vparty at any of thesaid stations may send an impulse of ringing current through thekick-coil to cause the latter to throw a drop connected with the trunkline at the magneto exchange.

' 7. An intercommunicating telephone system having a plurality of locallines common to a plurality of stations, a trunk line extending from theintercommunicating system to a magneto exchange, a ringer bridged acrossthe trunk line at the intercommunicating system whereby the operator atthe magneto exchange may signal a party at the intercommunicatingsystem, a re eating coil inductively connecting one o the said locallines with the trunk line for talking purposes, and a condenserconnected in series with the trunk-line side of the repeating coilwhereby any considerable portion of the ringing current sent from themagneto exchange toring the said ringer is prevented from flowingthrough the repeating coil.

8. n intercommunicating telephone system having a local line common to aplurality of stations, a trunk line extending from theintercommunicating system to a magneto exchange, a re eating coilinductively connecting the said ocal line with the trunk line fortalking purposes,'a condenser in circuit with the trunk-line side of therepeating coil to permit talking currents to pass through the repeatingcoil, but being of small enough capacity to prevent any considerableamount of signahng current from passing through the repeating coil, aringer bridged across the trunk line at the intercommunicating systemfor receiving incoming trunk calls, and a kick-coil at theintercommunicating system, the secondary of which is bridged across thetrunk line whereby a party at the intercommunicating system may cause animpulse of current to be sent over the trunk line to throw a dropconnected with the trunk line at the magneto exchange.

9. In a telephone system, a trunk line and a local line inductivelyconnected for conversation by a repeating coil, a condenser of smallcapacity in series with a winding of the repeating coil whereby anyconsiderable quantity of signaling current is prevented from passingthrough the repeating coil, a kick-coil associated with the trunk lineat the local line whereby an impulse of current may be sent over thetrunk line for signaling from the local line to an exchange, and aringer associated with the trunk line at the local line'for receivingsignals sent to the local line over the trunk line.

10. An intercommunicating telephone system having a plurality of locallines common to a plurality of stations, one of which stations isdesignated an attendants station, a trunk line extendingfrom theintercommunicating system to a magneto exchange, a repeating coilinductively connecting one of the local lines with the trunk line fortalking ism at the attendants station whereby the attendant may signalany of the other stations of the intercommunicating system to answer anincoming trunk call, and suitable mechanism at the Various stations ofthe intercommunicating system whereby a party at any of the stationsthereof may connect his telephone set with the last mentioned local linefor conversation over the trunk line.

1l. In a telephone system, a trunk line, a local line extending to aplurality of stations of an intercommunicating system, a repeating coilinductiyely connecting the trunk line with the local line forconversation, a kick-coil associated with the trunk line at the localline, means at each of the Said stations controlling the kick-coilwhereby an impulse of current may be sent over the trunk line from anyof the said stations, 'for signaling from the local line to an exchange,and a signaling device associated with the trunk line at the local linefor receiving signals sent to the local line over the trunk line.

l2. In a telephone system, a trunk line, a local line extending to aplurality of stations of an intercommunicating system7 a repeating coilinductively connecting the trunk line with the local line forconversation, a condenser of small capacity in series with a winding ofthe repeating coil whereby any considerable quantity of signalingcurrent is pre- Vented from passing through the repeating coil, and asignaling device bridged across the trunk line at the local line forreceiving signals sent to the local line over the trunk line.

18. In a telephone system, a trunk line, a local line extending to aplurality of stations of an intercommunicating system, a repeating coilinductively connecting the trunk line with the local line forconversation, a condenser of small cal'iacity in series with a windingof the repeating coil whereby any considerable quantity of signalingcurrent is prevented from passing through the repeating coil, akick-coil associated with the trunk line at the local line, and means ateach of the said stations controlling the kick-coil whereby an impulseol current may be sent over thc trunk line from any of the saidstations, for signaling from the local line to an exchange.

14. An interior telephone system including a plurality of stations, atrunk line leading to an exchange, a switching key at an interiorstation being adapted to have at least two operating positions, in oneof which it is adapted to connect an interior system ,with said trunkline, a signal device at the exchange end oi the trunk linc adapted tore` spond to impulses of current, a primary kiel: coil circuit which isclosed by said switching key when occupying a diil'erent operatingposition, and a secondary kiek coil circuit in inductive relation withsaid primary kiekI coil circuit and including the signal device at theexchange end of said trunk line.

As inventor of' the foregoing l hereunto subscribe my name, in thepresen e of two subscribing witnesses, this (ith daiif May, 1908.

ELME t It. COlWlN.

YVitnesses Y FREDERICK li. PARKER, FRANK J. RYAN.

